Process for making acetyl benzoyl peroxide



Patented Jan. 1,

ing acetyl benzoyl peroxide r invention isan improved process for malt- The process broadly consists in oxidizing mixtures of benzaldehyde and acetic anhydride in the presence of certain catalysts or promoters, all as more fully he're1limiter?described. A

This reaction, however, is erratic, and, even when carried out using the purest of starting materials, it results in yields 01' the product which are too low for successful commercial production. These factors have made thecommercial production of acetyl benzoyl peroxide by known methods difficult and expensive.

It is a principal object of this invention to provide an improved, efficient and economical process for making acetyl benzoyl peroxide in good yields. The advantages of the process of this invention will be apparent.

The invention may be practiced by employing oxygen, air, or other oxygen-containing gases to oxidize mixtures of benzaldehyde and acetic anhydride which contain a small quantity of dibenzoyl peroxide as a catalyst or promoter ior the reaction. The quantity of dibenzoyl peroxide used may vary from about 0.25% to about 1.0% by weight of the total reaction mixture, and about 0.5% to about 0.75% is preferred. There is no reason to believe that amounts of dibenzoyl peroxide greater than 1% would be harmfulin the process, but such amounts seem to be unneces- UNITED STATES "PATENT*OEF-l E PROCESS FOR MAKING: AOETYL' BENzoYn Thomas'F. Canuthers,-"South rl e s ton,-W vai. "assignor" to -Carbide andCarbon Chemicals} it.:Corporation,'a'corporation ol' New York 1 NoiJrawihgl .Application December 22.19%3, 'S erialNo. 703,599

' GCIaimS. .;(C].

' in nowise restricted to any theory Tofiits opera pr ssfis not und r odtaa thisinven pn is tion.

a On y s i slie fir fil'fi invi tic ia s the fact that contrary to what might-beexpegted from the action. pfj diben zoylperoxidef s a catae lyst or promoter, the additionof-pre'viously re; a ac t b z y pcrqxide q h eaq iq i do o sa sfactori atal r m t it zdocs yhp r x de- 1...; v

By h used, fr csssa is actqrx i l... .I acetyl benzoyl peroxide'are consistently obtained whether extremely pure or technical grades or raw materials are used. In all cases, the yields secured by the use of this process are much higher than could be obtained under the best of conless time is required to completethe reaction'in the case of the new process, and smaller excesses of acetic anhydride are necessary for the reaction. One method of carrying out this invention may be asfollowsz The mixture of benzaldehyde and acetic anhydride may be placed in a glass or aluminum tube to provide a column of liquid. Air or oxygen ditions using previously known methods. Also,

may then be admitted finto the bottom of the tube. through a ceramic diffuser, and passed up through the column of liquid. It is desirable to control the temperature of the reaction mixture so that it does'not rise above about 40 C., and a temperature of about 35 0., is preferred. Samples from the mixture may be analyzed at intervals, and the reaction is stopped when there is no further increase in the amount of acetyl benzoyl peroxide formed. The product may be recovered by chilling the reaction mixture until the acetyl benzoyl peroxide is crystallized. The crystalsare then filtered from the liquid under pressure.

Specifically, reactions were conducted in the system described above using. an aluminumtube providedlwith a water jacket to eifect temperature control of the reaction.

The results of six representativeruns are shown below in tabular form. In four ofthese reactions the best practice according to the previously known processis illustrated, whi1e in direc com-51' therewith are shown the data from two runs made in accordance with this invention.

dibenzoyl peroxide at a temperature below about 40 C.

Run No. 1 2 3 4 5 6 Benzaldehyde, wt. parts. 400 403 475 400 400 585 Acetic enhydride wt. par 1, 001 1,014 1, 150 1, 000 1, 080 840 Molar ratio bemameilyde 1:2. 6 1:2. 6 1:2. 5 1:2. 6 1:2. 8 1:1. 5

anhydnde Dibenzoyl peroxide, wt. parts None. None None None 10 10 Dibenzoyl peroxide, percent total charge. 0. 68 0. 86 Source of oxy n Air. Air Air. Pure oxygen. Air. Air. Reaction ,ternperaturg, G U H p H v 35 35 a 35 -35 35 35 Duration geaction hr v I V 12.5 6. 75 21. 5 24 18. 5 23. 5 Crude reactionproduct; wt. parts 1, 401 1, 417 1,625 1, 400 I 1, 371 1, 426 Percent acetyl benzoyl peroxide in crude product 21. 5 17. 2 22. 2 20. 4 44. 3 62. 5 Percent yield of acetyl benzoyl peroxide (based on benzaldehyd 44. 5 35. 7 44. 8 42. 2 89. 4 B9. 7

' Air in this run was dried by passing-through calcium chloride towers. 1 I

It will be readily apparent from these data that this invention has provided very material irisprovements in the process of making acetyl hen zoyl peroxide. Modifications Of ffilliS process are possible without departing from the invention, and. are included within its scope asdefined by the appended claims. I claim: 4 1 1. Process for making acetyl benz oyl peroxide which comprises reacting upo'n 'benzaldehyde and acetic 'a-rihydrided with-an oxygen-containing gas in the presence of dibenzoy-l peroxide. v

2. Erocess ior making acetyl benzoyl peroxide which comprises reacting upon benzaldehyde and acetic anhydride with an oxygen-containing gas in the presence of'about ;;25% to about 1.0%0: dibenzoylperoxide.

'3; Process for making acetyl benzoyl peroxide which compriees rea'cting-upon benzaldehyde and acetic anhydride with an oxygen-containing gas in thepresence 'of'about '0.25% to about 1.0% of 4. Process for making acetyl benzoyl peroxide which comprises passing air through a mixture of henzaldehyde, and acetic anhydride which contains .a .smallamount of dibenzoyl peroxide, and thereafter separating acetyl benzoyl peroxide irorn said mixture;

5. Process for making acetyl benzoyl peroxide .-which'.comprises passing air through a mixture of benzaldehyde and aoetic anhydricle which contains from-about 0.25% to 1 1.0% of "di'b enzoyl peroxide, and thereafter separating acetyl "benzoyl peroxide from said mixture.

6. Process for makingacetyl benzoyl peroxide w ch comp ises pas ing ai th ou h a mixture of nza d hydeit e her with ajm a t ci'a yd de. it jinixture about 0.66% of dibenzovl'peroxide Qbern'g' main a ned ate em a ureioi e ut,.,3, Q- 

